1. Field of the Invention
This invention relates to crimping, and more particularly to a cable crimping tool and a method of forming a calibrated crimp in a cable splice connector positioned around a cable splice using said cable crimping tool.
2. Discussion of the Art
A cable as referred to herein, is an assembly of wire strands which may be used as electrical conductors and which have been laid up together into at least one core. Where there is more than one core, the cores are usually bundled or twisted together. Where there is more than one core and the cores are discrete electrical conductors, each core is electrically insulated from the others and laid up together, for example, by being bundled together or twisted around a central core. For the sake of simplicity and clarity, a reference to "cable" herein is meant to include a single-core cable or a multi-core cable. Likewise, a reference to "cable end(s)" herein is meant to include core end(s).
Cable ends may be spliced (i.e., united or joined) into in-line joints or splices in numerous ways. By way of illustration but not limitation, the strands may be interwoven (a braided lap joint), or spread apart somewhat and interdigitated (a crowsfoot lap joint), or knotted (a square knot joint). The ends may be lapped together (a simple lap joint), or butted together (a simple butt joint).
The permanence of cable splices may be improved by brazing the cable at or around the splice, soldering, welding, and the like, and/or by employing a mechanical connector, herein referred to as a "cable splice connector." The cable splice connectors discussed herein are cylinders of a mechanical malleable metal or alloy which are crimpable and which are positioned around a cable splice to surround it, usually by sliding the connector over one end of the cable before the splice is made. For applications where brazing the cable, soldering, welding, and the like, are not desirable, practical or feasible (e.g., cable splicing in underground mines where open flames are banned because of the presence of potentially explosive gasses), the strength of the joint may rely heavily on the cable splice connector and the quality of the crimp to the cable splice formed therein.
Cable connector crimping tools are known in the art and may be employed to securely fasten a crimpable cable splice connector to the cable splice. To "crimp" as used herein refers to pinching or pressing together two or more parts, at least one of which is malleable, in order to mechanically and/or electrically interconnect them. A crimping tool generally consists of a pair of dies which when closed around a crimpable cable splice connector positioned around a cable splice, pinches or presses together the connector and the cable splice contained therewithin, thereby firmly joining the parts together. The tool is subsequently removed. The tools discussed herein are of the type which are struck (as with a hammer). These are small, lightweight and easily transported, a distinct advantage over tools which are closed by other means, such as by a more massive vise which is turned, or by a plier-like pair of lever arms which tend to be long in order to provide the mechanical advantage required for closure.
Cable connector crimping tools are generally of two types, uncalibrated and calibrated. An uncalibrated crimping tool typically has a pair of dies, one die of which is a male (i.e., a convex shape), the other a female (i.e., a concave shape). When struck excessively, the connector and splice may be excessively thinned-out due to the malleable nature of most metals and some alloys. When this occurs the cable is weakened at the crimp. A calibrated crimping tool typically has a pair of dies, both of which are female dies (i.e., both concave shapes). When struck, these dies cannot be hammered down past a predetermined stop or stopping point and hence thinning-out of the connector and splice does not occur and the tool is said to produce a calibrated crimp. Calibrated crimping tools are clearly preferred.
Known calibrated cable connector crimping tools which are struck lack versatility in that each tool or pair of tool inserts crimp only one connector size. Examples of such one-size tools are the Burndy Beat Block BBM and the Burndy Hypress, both commercially available from the Burndy Corporation of Norwalk, Conn.